However, use of MHC congenics in our studies and in those of other investigators led to the conclusion that MHC alleles were not determinants for the differences in arthritis severity found 4 weeks following infection in C3H-H2k, C57BL/6-H2b, and DBA-H2d mice (Yang et al., 1992; Brown and Reiner, 2000). This evidence concerns the gene HLA-C and arthritic joint disease.